Electron donor compounds, also known as Lewis Bases, have been widely used in catalyst systems (1) as an electron donor in the solid component of the catalyst system comprising a halogen-containing Ti compound supported on an anhydrous activated Mg dihalide compound and (2) as an electron donor with the co-catalyst component comprising an organometallic compound, to increase the activity and stereospecificity of the catalyst for the polymerization of alpha-olefins, in particular propylene and higher alpha-olefins.
Conventional classes of electron donor compounds known in the art include ethers, ketones, amines, alcohols, phenols, phosphines and silanes. Examples of such electron donor compounds and their use as a component of the catalyst system are described in U.S. Pat. Nos. 4,107,414, 4,186,107, 4,226,963, 4,347,160, 4,382,019, 4,435,550, 4,465,782, 4,472,524, 4,473,660, 4,522,930, 4,530,912, 4,532,313, 4,560,671, and 4,657,882.
Electron donors consisting of organosilane compounds, containing Si--OCOR, Si--OR, or Si--NR.sub.2 bonds, having silicon as the central atom, and R is an alkyl, alkenyl, aryl, arylalkyl or cycloalkyl with 1-20 carbon atoms are known in the art. Such compounds are described in U.S. Pat. Nos. 4,347,160, 4,382,019, 4,435,550, 4,465,782, 4,473,660, 4,530,912 and 4,560,671 where they are used as an electron donor in the solid catalyst component; and U.S. Pat. Nos. 4,472,524, 4,522,930, 4,560,671, 4,581,342 4,657,882 and European Patent applications 45976 and 45977 where they are used as an electron donor with the co-catalyst.
However, in all of the above catalyst systems in which an organosilane compound is used, none describe organosilane compounds containing Si--N bonds where the nitrogen bonded to the silicon atom is a nitrogen of a nitrogen containing heterocyclic ring.